"While marijuana may also have some negative consequences, it definitely is nowhere near the negative consequences of alcohol," study co-author told Kent Hutchison told Medical News Today.

He said previous research showing links between reduced brain matter and cannabis use was inconclusive.

"When you look at these studies going back years, you see that one study will report that marijuana use is related to a reduction in the volume of the hippocampus. The next study then comes around, and they say that marijuana use is related to changes in the cerebellum…

"The point is that there's no consistency across all of these studies in terms of the actual brain structures."